500E motor swap to 119.972

[harrycarry250]

Hello all,

1993 500E owner here and I just embarked on a motor swap on 1993 500E. Today I began inspecting my two engines, the donor and the original to see what I would need to transfer over between the two. One glaring issue came up that I plan on remedying with a bit of ingenuity and DIY machining but I am curious if anyone else has come up against this.

On the original motor, I have a crank position sensor of sorts on the harmonic balancer. On the donor motor which I believe to be a 119.972 (will confirm) there is a totally different style harmonic balancer and no sensor. In addition to this, the timing cover is not provisioned for a sensor mount at all, and neither is the harmonic balancer.

I plan on swapping harmonic balancers between the motors and then modifying a mounting tab that would have been used to mount the sensor on the 'new' motor.

I am curious if anyone has encountered this issue before, and if so what did you do to remedy it, and did the motor put up any more fights further down the road?

See attached photos

Thank you

 

[r44raven]

If the 119.972 is from an R129, then it should be a straight swop. I did this some years ago on my 500E, when I discovered that some idiot previous owner had installed a 4.2 V8 (one assumes because the original engine had failed and the 4.2 was a readily available cheap alternative?). At the time of my discovery, there were no original 119.974s to be had, so I bought an R129 and under gsxr's expert guidance, did the swop. It was done by my local MB independent, and I don't recall any of the problems you indicate. The only issue was the fan clutch had to be swopped, as it is deeper on the 119.972, and caused the fan to foul the radiator on heavy braking.

 

[gsxr]

harrycarry250, the front crank sensor is for diagnostics only. This sensor was discontinued as of facelift production (May/June 1993). You don't need it. If you follow the wire on your 500E, you'll find it dead-ends at the diagnostic port near the EZL / ASR pump area.

And you don't need to swap balancers either. The later 1-piece style with "open" balancer is easier to R&R, as it's a slip-fit design. The earlier 2-piece balancer/hub is press-fit and requires heating the hub before installing. This change occurred somewhere in 1994 or 1995, I forget exactly when.

 

[harrycarry250]

Thank you all, and gsxr I did notice that just now after looking back at all my pre-removal photos. This makes my life 200 times easier in so many ways, as per r44 I will change over the fan clutch. Thank you r44 for the information, I am happy to hear your swap went well. Has your car been reliable ever since?

Just going to do some resealing, swap VC's, swap fans, and accessories, and plop in the new motor! I am sure I am missing some stuff but overall that's the jist. Going to work out how to disable secondary air also.

 

[TerryA]

Thank you all, and gsxr I did notice that just now after looking back at all my pre-removal photos. This makes my life 200 times easier in so many ways, as per r44 I will change over the fan clutch. Thank you r44 for the information, I am happy to hear your swap went well. Has your car been reliable ever since?

Just going to do some resealing, swap VC's, swap fans, and accessories, and plop in the new motor! I am sure I am missing some stuff but overall that's the jist. Going to work out how to disable secondary air also.

@harrycarry250,
What do you mean by “Going to work out how to disable secondary air also”? I’ve never heard that term in my 19 years of 500E ownership. What secondary air?

lol

 

[gsxr]

I think he means the air pump / smog pump that runs for a few minutes after a cold start. It's easy to disconnect, but on USA models it will trigger a CEL.

 

[harrycarry250]

Yep that is what I'm referring to. Secondary air injection is just another term

 

[r44raven]

Thank you all, and gsxr I did notice that just now after looking back at all my pre-removal photos. This makes my life 200 times easier in so many ways, as per r44 I will change over the fan clutch. Thank you r44 for the information, I am happy to hear your swap went well. Has your car been reliable ever since?

The swop was a complete drivetrain (engine and transmission) change. It has proved 100% successful, and I have driven some 20,000 miles trouble free since the 119.972 was installed. As I recall, the only "glitch" engine-wise during that time was a minor misfire, cured by fitment of new spark plug leads.

I do worry a little about how this installation might affect the resale value of the car? On the upside, the mileage on the car at the time of the swop was some 160k - and it now benefits from an engine/transmission from the R129 which had only clocked 80k miles. On the downside, the engine is not an original 119.974.

Any thoughts, anyone?

 

[gsxr]

I do worry a little about how this installation might affect the resale value of the [500E]? On the upside, the mileage on the car at the time of the swop was some 160k - and it now benefits from an engine/transmission from the R129 which had only clocked 80k miles. On the downside, the engine is not an original 119.974.

Any thoughts, anyone?

Since the 500E isn't a low-mile garage queen with ~180kmi total, I don't see the .974 --> .972 engine swap affecting value at all. The engines are functionally identical, and since the new powertrain has 80k fewer miles, if anything it might be considered a perk by future buyers.

 

[sheward]

Agree. It might add value to me personally if I were a buyer. It's likely additional maintenance was performed with the engine out.

 

[r44raven]

Is there any update on this swop?

 

[harrycarry250]

Yep,

The swap has been completed and I have the car in a running and driving condition right now. I am just finishing up some details that are not swap related -- your typical 'while you're there' items.

There were not any major issues with the swap that have not been outlined already here, feel free to ask any question though.